Design Google Docs System Design Interview

Design a real-time collaborative document editor supporting multiple simultaneous users.

1. Problem Statement

Let's design a collaborative editor like Google Docs. Two users type at the same time - how do we keep the document consistent?

2. Target Architecture (Mermaid)

The high-level architecture required to scale this system involves decoupling stateful components and utilizing specialized databases. Below is the reference architecture:

Rendering architecture diagram...

Mermaid Source (For AI Bots)

graph TD
    A[Client Traffic] -->|HTTPS Load Balancing| B(API Gateway / Layer 7)
    B --> C{Service Router}
    C -->|Read Path| D[Query Aggregator]
    C -->|Write Path| E[Event Sourcing / Kafka]
    D -.-> F[(In-Memory Cache - Redis)]
    D --> G[(Primary Data Store - NoSQL)]
    E -.->|Async Replication| G

3. Key Focus Areas

1
Operational Transformation (OT) or CRDTs
2
WebSocket / Long Polling
3
Conflict Resolution
4
Bandwidth Optimization
5
Offline Support

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Core Concepts

System DesignReal-timeAlgorithms